1. Field of the Invention
The present invention relates to apparatus and methods of surface imprinting films, and more specifically, films surface imprinted with nanometer-sized particles including multi-walled carbon nanotubes (MWNT) for military, commercial and recreational applications including, but not limited to, photovoltaic devices.
2. Description of the Prior Art
There is an ongoing worldwide effort within the field of nanotechnology to shrink the feature sizes of present devices thus leading to improved devices that have lower mass and volume. There is great interest in new processes for production of nanoscale features. Important new processes being developed are methods known as nano-imprinting lithography (NIL) and molecular imprinting (MI). In NIL, basically, a silicon wafer bearing a pattern produced by electron-beam lithography is used to imprint the pattern into a soft polymer film. Typically, in the molecular imprinting processes, a cross-linking polymerization of a mixture of a molecule of interest, a monomer and porogen is performed, followed by extraction of the molecule of interest, which leaves a porous polymer with imprints of the molecule of interest over its surface.
Efficient fabrication of integrated circuits requires reliable, high-throughput processing to form device elements and interconnects. The most successful patterning technique used over the past several decades has been photolithography, although developments in this technique have pushed feature resolution to the 40 nm range and have come at the expense of increasingly complex and costly fabrication equipment. To address these problems, significant effort has been placed on developing alternative methods of nanoscale patterning, including electron-beam and nanoimprint lithography. Nano-imprinting lithography (NIL), proposed in 1995, is an especially interesting approach for nanoscale pattern generation since it is in principle scalable, parallel, and cost-effective. NIL has been used most widely for creating features with a resolution of 100 nm.
In NIL, a resist relief pattern is generated via compression molding (or embossing) of a deformable polymer by a hard inorganic stamp, rather than by modifying the resist chemical structure with radiation or self-assembly. This pattern is typically transferred to the underlying substrate by anisotropic reactive ion etching (RIE), followed by material deposition and liftoff of the remaining polymer. In general, polymers used for NIL must be heated above the glass transition temperature (ca. 200° C.) to enable flow during the imprinting step. This heating process limits the application of NIL to flexible plastic substrates envisioned for a broad range of emerging applications, since many of these plastics deform at elevated temperatures. Interestingly, recent studies have reported room-temperature nanometer-scale imprinting of polymers on silicon substrates, although the procedures were not elaborated by subsequent etching and deposition. (Khang, et al., Adv. Mater 2001, 13, 749; and Behl, et al., Adv. Mater 2002, 14, 588.)
Since imprint lithography is not based on modification of resist chemical structure by radiation, its resolution is immune to many factors that limit the resolution of conventional lithography, such as wave diffraction, scattering and interference in a resist, backscattering from a substrate, and the chemistry of resist and developer.
Molecularly imprinting polymers (MIPs) are of growing interest for their potential application for advanced materials for solid-phase extraction and thin coatings for sensor devices. In most cases, the templates used for the synthesis of imprinted polymers are subnanometer molecules, including solvents, toxic components, or drugs.
Current organic solar cells include thin layers of an electrode that sandwich polymer composite sheets. When sunlight hits the sheets, they absorb photons, exciting electrons in the polymer and the molecule of interest, which makes up about 90% of the composite. The result is a useful current that is carried away by the electrodes.
U.S. Pat. No. 6,517,995 issued on Feb. 11, 2003 to Jacobson et al., that teaches an elastomeric stamp, which facilitates direct patterning of electrical, biological, chemical, and mechanical materials. A thin liquid film is patterned by embossing with a patterned elastomeric stamp. The patterned liquid is then cured to form a functional layer. This technique is limited in that it requires a elastomeric stamp and thus the degree to which the relative geometry of nanoscale components are in registry is limited by the ability to position the stamp from layer to layer.
From the foregoing, it will be appreciated that there is a need in the art to develop micro- and nano-structured electron and hole collecting interfaces for fabrication of low mass, low volume, nanofluidic devices and a variety of thin-film electronic devices. The present invention is directed to overcoming one, or more, of the problem set forth above.